The current invention proposes interstitial administration of therapeutically effective doses of certain sesquiterpene epoxides (trichothecenes) to achieve ablation of non malignant cells in a selected organ or internal tissue mass.
Surgery remains the primary mode of ablation of non malignant tissue. The trend in prior art has been toward minimally invasive surgery through the use of various devices that can be inserted through small incisions or natural body orifices to reach and destroy the desired tissue. These devices employ a variety of means for ablation of tissue including cutting implements, devices for heating tissue, and devices for freezing of tissue. The destruction of tissue by these means results in cell death through necrosis.
Present invention departs from prior art in two significant respects. First, it provides a means of chemosurgery for ablation of tissue. Second, it provides a means of ablation that is accomplished by apoptosis versus prior art""s necrosis. The advantages of apoptosis over necrosis will be discussed later in this application.
Prior art ablation of internal tissues can broadly be divided into three categories; Conventional Surgery, Minimally Invasive Surgery, and Minimally Invasive Non Surgical Ablation.
Conventional Surgery involves making a significant incision through the skin and all underlying layers of tissue to reach a desired organ or tissue mass. All or portion of the organ or tissue mass is then cut and removed.
Minimally Invasive Surgery involves making a small incision or using an existing body orifice, insertion of a endoscope or laparoscope fitted with grasping and cutting tools or similar device, and ablation of a desired tissue mass by cutting.
Minimally Invasive Non Surgical Ablation involves insertion of devices other than grasping and cutting tools to destroy a target tissue mass.
Since applicant could not find any comparable prior art methods using chemosurgery for the more common procedures envisioned under present invention, the closest prior art comparable is Minimally Invasive Non Surgical Ablation. Consequently, a further discussion of prior art Non Surgical Ablation follows.
Non Surgical Ablation devices are generally tailored to the condition being treated or tissue mass targeted for ablation. Examples of prior art methods for treating two common conditions are presented below for illustrative purposes. Later, in the reduction to practice portion of this application, composition and methods for treating these conditions using apoptotic chemosurgery will be presented to contrast the novelty and utility of present invention""s methods over prior art.
Benign Prostatic Hypertrophy (BPH)
An estimated 50% of men have histologic evidence of BPH by age 50, which increases to 75% in men older than 80 years of age. In 40-50% of these patients BPH becomes clinically significant. The prostate is a chestnut shaped body surrounding the beginning of the urethra in the male. The adult prostate weighs about 20 grams. In most men the prostate begins to enlarge further as they age. Prostatic enlargement compresses the urethra and may interfere with urination. BPH is characterized by an increased number of epithelial and stromal cells which may be the result of impaired programmed cell death (Steinbecker et. al. eMedicine Journal, Vol. 3, No. 1, Jan. 10, 2002).
Conventional surgery to remove all or part of the prostate is called a retropubic prostatectomy and involves making an incision in the abdomen and removal of prostatic tissue by hand and cauterization of bleeding vessels.
Minimally invasive surgery is called transurethral resection of the prostate (TURP). A resectoscope is passed up the urethra, a cutting edge or heated wire loop is then used to cut away as much of the prostatic tissue as possible, and a catheter is left in the urethra for several days as it heals.
Non surgical ablation methods employed under prior art include Transurethral Microwave Thermotherapy of the Prostate (TUMT), Transurethral Needle Ablation of the Prostate (TUNA), and Transurethral Laser Incision of the Prostate (TULIP).
TUMT involves insertion of a specially designed Foley-type catheter into the bladder allowing a microwave antenna to be properly positioned. TUMT uses microwaves in the 900-1100 kHz spectrum to create heat for the destruction of prostatic tissue (Rubenstein, xe2x80x9cTransurethral Microwave Thermotherapy of the Prostate (TUMT)xe2x80x9d, eMedicine Journal, Vol. 2, No. 6, Jun. 29, 2001).
TUNA operates at 490 kHz and uses two needles deployed from the catheter tip as electrodes. As the prostate cells resist the passage of current between the two needle electrodes, heat is produced, resulting in necrosis of the tissue (Steinbecker, xe2x80x9cTransurethral Needle Ablation of the Prostate (TUNA)xe2x80x9d, eMedicine Journal, Vol. 3, No. 1, Jan. 10, 2002).
TULIP is also mentioned in prior art. TULIP employs a laser. Lasers heat tissue, once again inducing necrotic cell death.
Under present invention, therapeutically effective amounts of trichothecene would be injected into the prostate to achieve a desired amount of ablation. Since compositions of present invention induce apoptosis, they would be much less traumatic than the necrotic methods employed under prior art.
Liposuction
Liposuction is the most commonly performed cosmetic procedure in the US.
Traditional liposuction involves insertion of a cannula through an incision. The cannula is a hollow tube with one or more openings for breaking down tissue and a vacuum is provided for aspiration. The cannula is moved back and forth repeatedly to rasp off and aspirate fat cells.
Internal Ultrasound Assisted Liposuction uses a cannula capable of emitting mechanical vibration energy greater than 16 kHz to enhance fat removal. The goal of using ultrasound is to achieve emulsification by microcavitation. Alternating compression and expansion cycles create microbubbles during the expansion cycle and as the bubble collapses during the compression cycle core temperatures may momentarily reach 72,000 Kelvin or higher resulting in a pulse of electromagnetic radiation termed sonoluminescence. Although Ultrasound Assisted Liposuction has the potential for less connective tissue damage than conventional liposuction, it requires continuous infusion of a wetting solution to conduct the sound waves. Additionally, short term complications include high rates of seromas and skin burn and long term issues involve concerns about DNA damage (part of the sonoluminescence is in the soft X-Ray range) and sonochemical effects such as disruption of chemical bonds resulting in the formation of free radicals and other reactive ions (Baxter, xe2x80x9cLiposuction Techniques: Internal Ultrasound Assistedxe2x80x9d, eMedicine Journal, Vol. 2, No. 10, Oct. 22, 2001)
Under present invention, therapeutically effective amounts of trichothecene would be injected into a given area to achieve a desired amount of ablation. Since compositions of present invention induce apoptosis, they would be much less traumatic than the necrotic methods employed under prior art. Present invention would also not harm any connective tissue as compositions of present invention function only on nucleated cells.
Because present invention operates by apoptosis versus prior art""s necrosis a brief discussion of both is presented to demonstrate the significant utility of present invention""s method of cell death over prior art""s method of cell death.
Necrotic death occurs when a cell is injured by oxygen deprivation or by a physical assault such as that from surgical procedures. Swelling and inflammation are hallmarks of necrosis. Directly damaged cells that are ruptured spill their contents into the surrounding area. Partially damaged cells that are no longer able to control their fluid and ion balance swell and rupture as charged particles such as sodium and calcium ions that are normally pumped out, now stream in. Inflammation begins as macrophages and other white blood cells of the immune system converge on the necrotic cells. The activation of an immune response to the injury initiates numerous events that range from secretions of the white cells that cause further damage to normal tissue in the vicinity of the injury to the production of growth and other factors to facilitate regrowth as part of an xe2x80x9cinjury responsexe2x80x9d.
A cell undergoing apoptosis sees very different changes. There is no swelling and no inflammatory response. Instead the dying cell shrinks and pulls away from its neighbors. Some of these shrunken apoptotic cells are ingested by neighboring cells. Dying cells that are not consumed may undergo further changes dividing into a number of xe2x80x9capoptotic bodiesxe2x80x9d that are removed quietly (Duke et. al., xe2x80x9cCell Suicide in Health and Diseasexe2x80x9d per IDS).
The compositions proposed under present invention are protein synthesis inhibitors (PSIs). Accordingly a brief background about protein synthesis and cellular function is presented.
The most fundamental function a cell is protein synthesis (i.e. expression of its DNA). Proteins make up xcx9c60% of a dry cell""s mass by weight. In very broad and general terms, as cells mature and differentiate in the body, they reach an equilibrium in protein synthesis and protein degradation and settle down to perform their given function in this relative state of homeostasis. There are two notable exceptions that cause massive perturbations to this homeostasis: 1) when a cell is called upon to grow and divide and 2) when certain secretory cells are called upon to produce large amounts of proteins for secretion. Although the cell signaling signaling pathways, intracellular transduction pathways, and spectrum of protein(s) to be produced are quite different in growth versus secretion, normal growth and secretion events share one major similarity in their end result: massively accelerated protein synthesis. A cell that is called on to grow (cycling cell) has as much as 5 times the protein synthesis activity of a non cycling cell and needs between 2,000 and 5,000 different enzymes and structural proteins to grow and divide. Likewise, secretory cells such as those of the immune system become protein factories producing massive amounts of antibodies, mediators, growth factors, or other proteins when stimulated to do so.
There are also abnormal conditions such as cancer and viral infections that share the same property of hyperactive protein synthesis versus normal quiescent cells. Viruses invade a cell, parasitize the host cellular machinery, and convert the cell into a factory producing massive amounts of viral proteins, much like a secretory cell. Cancer is a growth and divide type event, and even though the signaling mechanism is different in that it is self-induced intracellularly by several genetic mutations, the end result is also hyperaccelerated protein synthesis characteristic of a cycling cell.
Inhibiting protein synthesis effects cells in a dose dependent manner and effects actively cycling cells differently than non cycling cells. At low doses, protein synthesis inhibitors (PSIs) stop actively cycling cells from cycling without killing them (hereinafter referred to as inhibitory or G zero inducing dose). Inhibitory doses also stop hyperaccelerated protein synthesis by secretory cells. At moderate doses PSIs exhibit toxicity to actively cycling cells (hereinafter referred to as the cytotoxic dose). At high doses, PSIs exhibit toxicity to all cells (hereinafter referred to as the toxic dose).
Novelty and Unobviousness
First, present invention takes the novel approach by using chemosurgery for ablation of tissue versus prior art""s mechanical devices.
Second, present invention takes a novel approach of inducing apoptosis versus prior art""s methods of inducing necrosis.
Third, present invention also employs novel administration methods and dose levels of trichothecenes versus any of prior art""s uses of trichothecenes. Prior art has attempted using cytotoxic dose levels of trichothecene against hyperproliferative conditions such as cancer, however they have failed. Anguidine, a simple trichothecene, was tested against cancer and abandoned after Phase II testing showed a low tumor response and considerable hematologic toxicity. Prior art attempts to remedy this failure are embodied in U.S. Pat. Nos. 4,906,452 and 4,744,981 which propose conjugates of trichothecene with monoclonal antibodies to enhance delivery to the tumor and glycosylation of trichothecene to increase blood solubility. Present invention takes a novel and unobvious approach that is exactly opposite to prior art in several respects. First, present invention reverses direction of administration (i.e. administered from tissue side to blood versus prior arts direction of blood to tissue). Second, present invention embraces the non specific internalization properties to deliver the greatest doses to tissues it is applied to and depending on those tissues to retain the trichothecene, preventing the trichothecene from reaching general circulation (versus prior arts targeted delivery by monoclonal antibodies). Third, present invention embraces blood insolubility to prevent entry into the blood (versus prior art glycosylation). Fourth, present invention embraces the use of macrocyclic trichothecene (versus simple trichothecenes in prior art) because of enhanced localization attributes and narrower dose spectrum of biological effect (discussed later). Fifth, present invention administers toxic dose levels to target cell populations versus prior art""s cytotoxic dose levels.
Utility Over Prior Art
There are several distinct advantages to using apoptotic chemosurgery versus prior art""s mechanical devices and necrotic ablation methods.
First, apoptosis is a much cleaner method of cell death that does not result in swelling, inflammation, or an xe2x80x9cinjury responsexe2x80x9d. Swelling and inflammation result in pain as nerves are compressed, and as such apoptotic chemosurgery provides a much less painful alternative to necrotic surgery. xe2x80x9cInjury responsexe2x80x9d contributes to a cellularly xe2x80x9cmessyxe2x80x9d healing with potential overproduction of connective tissue, which would also be obviated by apoptotic chemosurgery.
Second, apoptotic chemosurgery does not cause any connective tissue damage as only nucleated cells are subject to death. Mechanical devices that cut or heat cause indiscriminate damage to all tissue.
Third, apoptotic chemosurgery does not cause the large scale damage to blood vessels that mechanical cutting, heating, grasping, or rasping devices do.
The combination of the above factors will provide for reduced procedure times, little or no hospital stay required, faster recovery times, and greater probability of long term therapeutic benefit being maintained versus prior art""s mechanical, necrotic, ablation methods.
Present invention proposes ablation of non malignant tissue cell populations by interstitial administration of therapeutically effective amounts of trichothecene.